Ok, thanks for clearing that up for me.
On Monday, July 19, 2021 at 4:56:51 PM UTC-5 ken...@cloudflare.com wrote:
> Sorry, I'm not sure what you mean. `myns::Person` isn't a real type, it's
> just an empty class that acts as a namespace containing the `Reader` and
> `Builder` types. `Reader` is your "handle to the data", and its getters are
> the only way to read the underlying data (the getters read directly from
> the raw underlying byte buffer).
>
> -Kenton
>
> On Mon, Jul 19, 2021 at 3:45 PM SR D <software.resea...@gmail.com> wrote:
>
>> Ok, so after some thinking, I can put something together to communicate
>> the type. Let's say I now know the type upon receiving the data, I make
>> this call ...
>>
>> auto m = reader.getRoot<Person>();
>>
>> Here, m is of type myns::Person::Reader. So although I know the type, I
>> looked at the person.capnp.h file and found no way to get a handle to the
>> actual data I care about, the myns::Person object, rather just the getters.
>>
>> I understand I can rebuild the object by calling the individual fields
>> like m.getXXX()'s, but I'm trying to do this in a generic way and not have
>> to call the individual fields to get a myns::Person and pass the object to
>> another thread for processing. So, my goal is to not have to call any proto
>> object methods (getters or setters) and hope to call something from the
>> Reader to get some sort of reference to the object since I know it's type.
>>
>> Is that possible?
>>
>>
>> On Saturday, July 17, 2021 at 12:22:10 PM UTC-5 ken...@cloudflare.com
>> wrote:
>>
>>> There is no way to find out a message's type if you don't know it
>>> already. So, you'll need to arrange to communicate the type yourself. The
>>> easiest way is to write an "envelope" message that is a union of all your
>>> other messages.
>>>
>>> struct OuterMessage {
>>> union {
>>> foo @0 :FooMessage;
>>> bar @1 :BarMessage;
>>> baz @2 :BazMessage;
>>> }
>>> }
>>>
>>> Then, always send OuterMessage as the top-level message type.
>>>
>>> -Kenton
>>>
>>> On Sat, Jul 17, 2021 at 11:55 AM SR D <software.resea...@gmail.com>
>>> wrote:
>>>
>>>> If the sender is sending any number of different data types that have
>>>> been serialized across the network, how does one know which type is coming
>>>> in so that it can be pulled off using FlatArrayMessageReader's::getRoot<>?
>>>>
>>>> E.g., say this while loop is constantly reading serialized data from
>>>> the network and results in a vector of message buffers.
>>>>
>>>> for (auto& msg : messages) {
>>>> auto arr = kj::ArrayPtr<const capnp::word>(
>>>> reinterpret_cast<const capnp::word*>(msg),
>>>> size / sizeof(capnp::word));
>>>>
>>>> capnp::FlatArrayMessageReader reader(arr);
>>>>
>>>> // how would one know what type to use here?
>>>> auto msg = reader.getRoot<?>();
>>>> }
>>>>
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